The invention relates to protective coatings. More particularly, the invention relates to the application of protective coatings to metallic substrates.
In the aerospace industry, it is known to apply protective coatings to metallic substrates. Exemplary coatings may be configured to provide one or more of wear protection, thermal protection, and chemical protection. Exemplary substrate materials are nickel-, cobalt-, and/or iron-based superalloys. Coating materials may vary by application. Exemplary wear coatings include carbide-based coatings and MCrAlY coatings. Such coatings may be applied as single layers or in multiple layers. MCrAlY coatings are also known for use as bond coat layers in multilayer thermal barrier coatings (e.g., having a ceramic top coat). Exemplary application techniques include high temperature spray methods such as high velocity oxy-fuel (HVOF) deposition.
It is often desirable to mask areas of the substrate during application of the coating so that the masked portions of the substrate remain uncoated. As applied, the coating often bridges between the substrate and adjacent portions of the mask. To withstand the temperatures of deposition, exemplary masks are metallic. Adhesion between the coating and the mask may, upon mask removal, produce chipping, delamination, or other damage of the coating along the substrate.
U.S. Pat. No. 6,592,948 of Fusaro, Jr. et al. identifies a multi-part/multi-step masking system for thermal barrier coatings. That exemplary system utilizes the combination of a metal foil sheet and a durable tape.